Is there a way to figure Overdrive or not at a certain speed?

Overdrive on my 97 is pretty high geared. Going down the road at 60mph, the slightest uphill, it lugs. Very high geared.

Here is a little test I do. I'm going down the road at 60mph, in Overdrive. I leave my foot at the same position. If I shift down to 3rd, I start to speed up. I then ease up on the gas a little. I'm now going down the road at the same speed (60), with my foot giving less gas.

I think I'm saving gas since I now have my foot on the gas less. But if you think about it, how could that be if I have Overdrive that's supposed to give me better mileage?

Is there anyway to know the gear ratios, and figure out from that, at what speed is better for Overdrive?

Is there anything else that I need to take into consideration, when using the test I do? Does it sound reasonable to think that driving down the road with the gas on less, in a lower gear is better?

Hope this makes seance, not sure I can explane what I'm trying to say.

I know we have some good trasnmission guys here:)

Chris.

No, O/D is electronically controlled for the most effficient operation based on engine load/speed.

Agreed... If you have the 2.84 Ratio, you'll be in the 1750-1850Rpm Range at 70 Mph... Yes thats a pretty tall gear ratio, and will lug the engine a bit... But rest assured the PCM like stated above will do everything it can to get the most of the economy... Going down to 3rd gear will only increase fuel consumption

Speed around her is 60mph. What RPM is it at, at 60mph? To low isn't good is it?
Thanks for the reply,
Chris.